Patent GB-1371111-A (GB)
Title: Remote detonation system
IPC: E02F5/30
Filed: 1972-10-13
Abstract: 1371111 Controlling and actuating by ultrasonic waves OKI ELECTRIC INDUSTRY CO Ltd and TAISEI CORP 13 Oct 1972 [15 Oct 1971] 47313/72 Heading G4F In a system for underwater explosive detonation employing ultrasonic signals, a control station emits frequency modulated command signals which are received by respective detonation control elements each arranged to detonate a respective body of explosive by energizing ignition means via a plurality of switches at. least one of the switches being closed by means of the command signals.  In a preferred embodiment the command signals are received by a main detonation control element which detonates its associated charge; each of a number of auxiliary detonation control elements receives the command signals and the shock front from detonation of the main charge and is thereby caused to detonate an associated auxiliary charge. The main control element may float near the surface of the water while the auxiliary control elements are disposed in a rock formation to be blasted (Fig. 2, not shown), or all the control elements may be disposed in the rock formation (Fig. 1, not shown). Control station (Fig. 3, not shown).-The carrier signal from an oscillator (12) is modulated (at 16) alternately by a signal f 1  from an oscillator (13) and a signal f 2  from an oscillator (14) which are connected in alternation by a timing gate circuit (15) to the modulator. The modulated signals are amplified and transmitted. The timing gate circuit (15) is described (Fig, 7, not shown) and comprises an arrangement of two timers (T 1 , T 2 ) and four relays (RL-1 to RL-4). Main detonation control element (Fig. 4, not shown).-The received command signals are demodulated (at 20) and the signals f 1 ,f 2  extracted in separate loops each including an appropriate bandpass filter (21 or 22), rectifying and integrating circuit (23 or 26) and amplifier (24 or 27). Thence, the processed signal f 1  operates a first switch (25) while the later-received processed signal f 2  operates a second switch (28) so that, with the two switches closed, a current source (29) is connected to a detonator (5). In a modification, in which a control station simultaneously transmits command signals, the main detonation control element is constructed to produce a delay so as to enable sequential closing of the two switches. To this end (Fig. 8, not shown) the output from the demodulator (20) is divided and passes, in one loop, through a filter (21), rectifying and integrating circuit (57) and Schmit trigger (59) to a first monostable multivibrator (61) whose output is connected to the first switch (25) as well as to the trigger input of a second monostable multivibrator (62) whose output forms one input to an AND-gate (64) whose output is connected to the second switch (28). The signal passes, in the other loop, through a filter (22), rectifying and integrating circuit (58) and Schmit trigger (60) to the second input of the AND-gate (64). Auxiliary detonation control element (Fig. 5, not shown). The command signals and the shock front from detonation of the main charge are received (as at 8). The command signals are processed in a first loop which may include a demodulator (32) and a bandpass filter (33) arranged to pass signal f 1 . Alternatively, the loop may comprise a mechanical or electrical timer which operates during the period of duration of the command signals. The output from the first loop is supplied to a first switch (36). The shock front signal is processed in a second loop comprising a limiter (38) which produces a pulse to close a second switch (37) so that, with both switches closed, current is supplied from a source (39) to a detonator (10). Various modifications of the main and auxiliary detonation control elements are described. An ignition circuit, for energizing a detonator upon receipt of two input signals (from the switches described) is also described (Fig. 6, not shown).  In another embodiment the detonation control elements are all in the form of the described main detonation control element, the auxiliary detonation control elements being omitted.